I in latter life decided my maths was not good enough, but to take an 'A' level maths course was over £100 but to take three 'A' level courses which included maths, was £20 so I did 'A' level art and Physics as well. I was surprised to find the 'A' level Physics book was wildly inaccurate on electrics, the diagram of how a fluorescent lamp works if followed it would either simply not work or go bang, as they had completely missed out the ballast.
However we would hope the teacher/lecture would point this out. The same happens on these pages within the forum, some one answers a question, then some one reading the answer notes an error and highlights it. But although we hope a book is proof read, it is very easy for errors to be made, and once published it is a bit late to highlight errors. The electrical regulations book has had 18 editions, and loads of amendments and error corrections, but it is not easy reading, one only needs to read this forum to see how people do not agree as to what it meant to say.
And the less complex books, electricians are unlikely to read them. Except maybe for a laugh as so many do get it completely wrong. However there are people who we do regard as being good with their Youtube channels at explaining what is required.
Watch John Ward's videos on youtube, there a good place to start
I would second that, he does come up on these pages, Big Clive is another, and eFIXX yet another. But there are also people who just like to hear their own voice,
this video from eFIXX goes over the reasons for having an EICR done they do many more, but it does give a feel of how a good youtube video should be like.
The major problem with DIY is test equipment, a full test kit would include a RCD tester, a loop impedance tester, an insulation resistance tester, and a low ohm meter, plus likely a clamp on ammeter. This is rather expensive, so the DIY person tries to reduce the test equipment, what I realised doing that collage course is how easy people make mistakes when connecting up a multi-meter, so I bought my own son a clamp on meter, as errors are less likely to damage you or the tester,
Big Clive does a video on testing multi-meters here and he shows using the meter I use,
which measures AC/DC amps, ohms, volts and non contact volts and costs around £35. The other cheap meter is the insulation resistance meter
also £35 but a RCD tester
and loop impedance meter get rather expensive. This
plug in tester costs around £43 from toolstation and the like, it does not really read low enough for the British ring final, but a proper loop tester will cost around £250 for cheapest, but even for the bare bones testers we are looking at over a £100, and so most DIY people try to make do with a simple multi-meter and I would say one of these
is a good start.
However what I am pointing out, safe DIY is not cheap, before you go off and buy your first book and start learning, one needs to be aware of the cost. One can hire test sets, however after each hire they need recalibrating so even to hire the cost is likely around £50 for the week.
Law wise, there is very little I can officially do without notifying, and in Wales it was £100 plus vat for first £2000 worth of work, plus if they feel you don't have the skill to inspect and test, they can charge for that on top, so it can cost more to DIY than getting an electrician who is a scheme member in to do it. England is a bit better, but I am sure most work is done illegally, if owner occupier who will find out? But you need to be aware before to lash out on books and equipment.